New Physics and the Solar Corona
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On the Solar Chromosphere Observed at the Limb with Hinode
The Astrophysical Journal, 719:469–473, 2010 August 10 doi:10.1088/0004-637X/719/1/469 C 2010. The American Astronomical Society. All rights reserved. Printed in the U.S.A. ON THE SOLAR CHROMOSPHERE OBSERVED AT THE LIMB WITH HINODE Philip G. Judge1 and Mats Carlsson2 1 High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, USA 2 Institute of Theoretical Astrophysics, P.O. Box 1029, Blindern, N-0315 Oslo, Norway Received 2010 March 8; accepted 2010 April 8; published 2010 July 21 ABSTRACT Broadband images in the Ca ii H line, from the Broadband Filter Imager (BFI) instrument on the Hinode spacecraft, show emission from spicules emerging from and visible right down to the observed limb. Surprisingly, little absorption of spicule light is seen along their lengths. We present formal solutions to the transfer equation for given (ad hoc) source functions, including a stratified chromosphere from which spicules emanate. The model parameters are broadly compatible with earlier studies of spicules. The visibility of Ca ii spicules down to the limb in Hinode data seems to require that spicule emission be Doppler shifted relative to the stratified atmosphere, either by supersonic turbulent or organized spicular motion. The non-spicule component of the chromosphere is almost invisible in the broadband BFI data, but we predict that it will be clearly visible in high spectral resolution data. Broadband Ca ii H limb images give the false impression that the chromosphere is dominated by spicules. Our analysis serves as a reminder that the absence of a signature can be as significant as its presence. -
Radiochemical Solar Neutrino Experiments, "Successful and Otherwise"
BNL-81686-2008-CP Radiochemical Solar Neutrino Experiments, "Successful and Otherwise" R. L. Hahn Presented at the Proceedings of the Neutrino-2008 Conference Christchurch, New Zealand May 25 - 31, 2008 September 2008 Chemistry Department Brookhaven National Laboratory P.O. Box 5000 Upton, NY 11973-5000 www.bnl.gov Notice: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The publisher by accepting the manuscript for publication acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. This preprint is intended for publication in a journal or proceedings. Since changes may be made before publication, it may not be cited or reproduced without the author’s permission. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or any third party’s use or the results of such use of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof or its contractors or subcontractors. -
What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?
The Astrophysical Journal Letters, 849:L7 (7pp), 2017 November 1 https://doi.org/10.3847/2041-8213/aa9272 © 2017. The American Astronomical Society. All rights reserved. What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun? Bart De Pontieu1,2 , Juan Martínez-Sykora1,3 , and Georgios Chintzoglou1,4 1 Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA 94304, USA; [email protected] 2 Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo, Norway 3 Bay Area Environmental Research Institute, Petaluma, CA 94952, USA 4 University Corporation for Atmospheric Research, Boulder, CO 80307-3000, USA Received 2017 June 22; revised 2017 October 5; accepted 2017 October 9; published 2017 October 23 Abstract Spicules are the most ubuiquitous type of jets in the solar atmosphere. The advent of high-resolution imaging and spectroscopy from the Interface Region Imaging Spectrograph (IRIS) and ground-based observatories has revealed the presence of very high apparent motions of order 100–300 km s−1 in spicules, as measured in the plane of the sky. However, line of sight measurements of such high speeds have been difficult to obtain, with values deduced from Doppler shifts in spectral lines typically of order 30–70 km s−1. In this work, we resolve this long-standing discrepancy using recent 2.5D radiative MHD simulations. This simulation has revealed a novel driving mechanism for spicules in which ambipolar diffusion resulting from ion-neutral interactions plays a key role. In our simulation, we often see that the upward propagation of magnetic waves and electrical currents from the low chromosphere into already existing spicules can lead to rapid heating when the currents are rapidly dissipated by ambipolar diffusion. -
Quiz 1 Feedback! Queries & Concerns Earth's Magnetic Field/Shield Quiz
Quiz 1 Feedback! Queries & Concerns • There is no protection on Earth from solar radiation. 1. What usually happens to energetic charged particles from the Sun when they approach the Earth? ! – Fortunately, this is not true! The Earths atmosphere absorbs high- energy electromagnetic radiation (such as X-rays from solar flares). !There is a continual flow of particles from the outer layers As for the energetic charged particles flowing from the Sun, the of the Sun, sometimes called the solar wind. We are Earths magnetic field provides a shield against them. Instead of protected from them by the Earths magnetic field, traveling straight through and hitting the Earth, they are redirected which deflects them away (changes their direction) so to travel along the field lines that bend around the Earth. that they dont hit the Earth head-on. Some of the particles – The ongoing, relatively thin flow of particles from the Sun is called travel along the field lines to the Earths magnetic poles, the solar wind. CMEs are rare, occasional events where a lot of where they collide with molecules in the atmosphere, mass is expelled in a short period of time. causing the Northern and Southern lights, the aurorae. – Some particles follow the field lines to the Earths magnetic poles; (Aside: The light is produced when electrons within the when they hit the upper atmosphere in the polar regions, they molecules are knocked up to higher energy states, and produce a glow we call the Northern/Southern Lights or aurorae. then fall back down, emitting photons of light.)! – Other particles are trapped in doughnut-shaped regions called the Van Allen belts. -
The Sun's Dynamic Atmosphere
Lecture 16 The Sun’s Dynamic Atmosphere Jiong Qiu, MSU Physics Department Guiding Questions 1. What is the temperature and density structure of the Sun’s atmosphere? Does the atmosphere cool off farther away from the Sun’s center? 2. What intrinsic properties of the Sun are reflected in the photospheric observations of limb darkening and granulation? 3. What are major observational signatures in the dynamic chromosphere? 4. What might cause the heating of the upper atmosphere? Can Sound waves heat the upper atmosphere of the Sun? 5. Where does the solar wind come from? 15.1 Introduction The Sun’s atmosphere is composed of three major layers, the photosphere, chromosphere, and corona. The different layers have different temperatures, densities, and distinctive features, and are observed at different wavelengths. Structure of the Sun 15.2 Photosphere The photosphere is the thin (~500 km) bottom layer in the Sun’s atmosphere, where the atmosphere is optically thin, so that photons make their way out and travel unimpeded. Ex.1: the mean free path of photons in the photosphere and the radiative zone. The photosphere is seen in visible light continuum (so- called white light). Observable features on the photosphere include: • Limb darkening: from the disk center to the limb, the brightness fades. • Sun spots: dark areas of magnetic field concentration in low-mid latitudes. • Granulation: convection cells appearing as light patches divided by dark boundaries. Q: does the full moon exhibit limb darkening? Limb Darkening: limb darkening phenomenon indicates that temperature decreases with altitude in the photosphere. Modeling the limb darkening profile tells us the structure of the stellar atmosphere. -
A Half-Century with Solar Neutrinos*
REVIEWS OF MODERN PHYSICS, VOLUME 75, JULY 2003 Nobel Lecture: A half-century with solar neutrinos* Raymond Davis, Jr. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA and Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA (Published 8 August 2003) Neutrinos are neutral, nearly massless particles that neutrino physics was a field that was wide open to ex- move at nearly the speed of light and easily pass through ploration: ‘‘Not everyone would be willing to say that he matter. Wolfgang Pauli (1945 Nobel Laureate in Physics) believes in the existence of the neutrino, but it is safe to postulated the existence of the neutrino in 1930 as a way say that there is hardly one of us who is not served by of carrying away missing energy, momentum, and spin in the neutrino hypothesis as an aid in thinking about the beta decay. In 1933, Enrico Fermi (1938 Nobel Laureate beta-decay hypothesis.’’ Neutrinos also turned out to be in Physics) named the neutrino (‘‘little neutral one’’ in suitable for applying my background in physical chemis- Italian) and incorporated it into his theory of beta decay. try. So, how lucky I was to land at Brookhaven, where I The Sun derives its energy from fusion reactions in was encouraged to do exactly what I wanted and get paid for it! Crane had quite an extensive discussion on which hydrogen is transformed into helium. Every time the use of recoil experiments to study neutrinos. I imme- four protons are turned into a helium nucleus, two neu- diately became interested in such experiments (Fig. -
Resolving the Solar Neutrino Problem
FEATURES Resolving the solar neutrino problem: Evidence for massive neutrinos in the Sudbury Neutrino Observatory Karsten M. Heeger for the SNO collaboration ............................................................................................................................................................................................................................................................ The solar neutrino problem are not features of the Standard Model of particle physics. In or more than 30 years, experiments have detected neutrinos quantum mechanics, an initially pure flavor (e.g. electron) can Pproduced in the thermonuclear fusion reactions which power change as neutrinos propagate because the mass components that the Sun. These reactions fuse protons into helium and release neu made up that pure flavor get out of phase. The probability for trinos with an energy of up to 15 MeY. Data from these solar neutrino oscillations to occurmayeven be enhanced in the Sun in neutrino experiments were found to be incompatible with the an energy-dependent and resonant manner as neutrinos emerge predictions of solar models. More precisely, the flux ofneutrinos from the dense core of the Sun. This effect of matter-enhanced detected on Earthwas less than expected, and the relative intensi neutrino oscillations was suggested by Mikheyev, Smirnov, and ties ofthe sources ofneutrinos in the sun was incompatible with Wolfenstein (MSW) and is one of the most promising explana those predicted bysolar models. By the mid-1990's the data -
Helioseismology, Solar Models and Solar Neutrinos
Helioseismology, solar models and solar neutrinos G. Fiorentini Dipartimento di Fisica, Universit´adi Ferrara and INFN-Ferrara Via Paradiso 12, I-44100 Ferrara, Italy E-mail: fi[email protected] and B. Ricci Dipartimento di Fisica, Universit´adi Ferrara and INFN-Ferrara Via Paradiso 12, I-44100 Ferrara, Italy E-mail: [email protected] ABSTRACT We review recent advances concerning helioseismology, solar models and solar neutrinos. Particularly we shall address the following points: i) helioseismic tests of recent SSMs; ii)the accuracy of the helioseismic determination of the sound speed near the solar center; iii)predictions of neutrino fluxes based on helioseismology, (almost) independent of SSMs; iv)helioseismic tests of exotic solar models. 1. Introduction Without any doubt, in the last few years helioseismology has changed the per- spective of standard solar models (SSM). Before the advent of helioseismic data a solar model had essentially three free parameters (initial helium and metal abundances, Yin and Zin, and the mixing length coefficient α) and produced three numbers that could be directly measured: the present radius, luminosity and heavy element content of the photosphere. In itself this was not a big accomplishment and confidence in the SSMs actually relied on the success of the stellar evoulution theory in describing many and more complex evolutionary phases in good agreement with observational data. arXiv:astro-ph/9905341v1 26 May 1999 Helioseismology has added important data on the solar structure which provide se- vere constraint and tests of SSM calculations. For instance, helioseismology accurately determines the depth of the convective zone Rb, the sound speed at the transition radius between the convective and radiative transfer cb, as well as the photospheric helium abundance Yph. -
An Introduction to Solar Neutrino Research
AN INTRODUCTION TO SOLAR NEUTRINO RESEARCH John Bahcall Institute for Advanced Study, Princeton, NJ 08540 ABSTRACT In the ¯rst lecture, I describe the conflicts between the combined standard model predictions and the results of solar neutrino experi- ments. Here `combined standard model' means the minimal standard electroweak model plus a standard solar model. First, I show how the comparison between standard model predictions and the observed rates in the four pioneering experiments leads to three di®erent solar neutrino problems. Next, I summarize the stunning agreement be- tween the predictions of standard solar models and helioseismological measurements; this precise agreement suggests that future re¯nements of solar model physics are unlikely to a®ect signi¯cantly the three solar neutrino problems. Then, I describe the important recent analyses in which the neutrino fluxes are treated as free parameters, independent of any constraints from solar models. The disagreement that exists even without using any solar model constraints further reinforces the view that new physics may be required. The principal conclusion of the ¯rst lecture is that the minimal standard model is not consistent with the experimental results that have been reported for the pioneering solar neutrino experiments. In the second lecture, I discuss the possibilities for detecting \smok- ing gun" indications of departures from minimal standard electroweak theory. Examples of smoking guns are the distortion of the energy spectrum of recoil electrons produced by neutrino interactions, the de- pendence of the observed counting rate on the zenith angle of the sun (or, equivalently, the path through the earth to the detector), the ratio of the flux of neutrinos of all types to the flux of electron neutrinos 1 (neutral current to charged current ratio), and seasonal variations of the event rates (dependence upon the earth-sun distance). -
19910023712.Pdf
SOLAR ASTRONOMY IX-1 Solar Astronomy 59-el N91-38026 Table of Contents 0. Executive Summary ................................ page 2 1. An Overview of Modern Solar Physics ......................... page 5 1.1 General Perspectives .............................. page 5 1.2 Frontiers and Goals for the 1990s ........................ page 8 1.2.1 The Solar Interior ............................ page 8 1.2.2 The Solar Surface ............................ page 9 1.2.3 The Outer Solar Atmosphere: Corona and Heliosphere ............ page 9 1.2.4 The Solar-Stellar Connection ....................... page 10 2. Ground-Based Solar Physics ............................. page 11 2.1 Introduction ................................. page 11 2.2 Status of Major Projects and Facilities ...................... page 11 2.3 A Prioritized Ground-based Program for the 1990s ................. page 12 2.3.1 Prerequisites .............................. page 12 2.3.2 Prioritization .............................. page 12 2.3.3 The Major Initiative: Solar Magnetohydrodynamics, and the LEST ....... page 12 2.3.3.1 The Large Earth-based Solar Telescope (LEST) ............ page 14 2.3.3.2 Infrared Facility Development .................... page 15 2.3.4 Moderate Initiatives ........................... page 15 2.3.5 Interdisciplinary Initiatives ........................ page 18 2.4 Conclusions and Summary ........................... page 20 3. Space Observations For Solar Physics ......................... page 20 3.1 Introduction ................................. page 20 3.2 -
What Controls Spicule Velocities and Heights? Color of R
ado. What Controls Spicule Velocities and Heights? Color of R. Hammer, A. Nesis Kiepenheuer-Institut furÄ Sonnenphysik University Abstract. Numerous mechanisms have been suggested to drive spicules. Many of them need a careful ¯ne-tuning of free parameters in order to achieve the basic characteristics, like velocity and height, of observed 2003 spicules. There might, however, be general physical mechanisms that control these properties. We show that whenever upper chromospheric Sun, plasma is exposed to a signi¯cantly non-hydrostatic pressure gradient, The it starts moving upward at the observed speeds. The plasma can reach & signi¯cant heights, at least if it receives some net chromospheric heat- ing during the rising phase. Therefore, such a hydrodynamic mechanism might help other (magnetic) drivers to control the basic properties of spicules. We suggest therefore to consider a new class of spicule driv- Systems, ing mechanisms, in which the plasma is not only accelerated by wave or magnetic forces from below, but also by the generation of a low pressure lar region above the chromosphere. Such a situation could arise e.g. due to Stel an instability in magnetic loops or as a result of the recon¯guration of open ¯eld lines. Stars, ol Co 1. Introduction on Classical spicules are needle-shaped chromospheric extensions, which can be seen in strong chromospheric lines to protrude out of the solar limb. They are highly dynamic and consist of plasma with properties characteristic of the upper 4 11 ¡3 Workshop chromosphere (temperature ¼ 10 K, electron density of order 10 cm ) that moves at supersonic speeds of 20 ¡ 30 km s¡1 up to heights of 5000 ¡ 10000 km, with a typical lifetime of 5 ¡ 10 min (e.g., Beckers 1972). -
Solar X-Ray Jets, Type-Ii Spicules, Granule-Size Emerging Bipoles, and the Genesis of the Heliosphere
SOLAR X-RAY JETS, TYPE-II SPICULES, GRANULE-SIZE EMERGING BIPOLES, AND THE GENESIS OF THE HELIOSPHERE Ronald L. Moore1, Alphonse C. Sterling1, Jonathan W. Cirtain1, and David A. Falconer1, 2, 3 1 Space Science Office, VP62, Marshall Space Flight Center, Huntsville, AL, 35812, USA: [email protected] 2 Physics Departrment, University of Alabama in Huntsville, Huntsville, AL 35899, USA 3 Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899, USA ABSTRACT From Hinode observations of solar X-ray jets, Type-II spicules, and granule-size emerging bipolar magnetic fields in quiet regions and coronal holes, we advocate a scenario for powering coronal heating and the solar wind. In this scenario, Type-II spicules and Alfven waves are generated by the granule-size emerging bipoles in the manner of the generation of X-ray jets by larger magnetic bipoles. From observations and this scenario, we estimate that Type-II spicules and their co-generated Alfven waves carry into the corona an area-average flux of mechanical energy of ∼ 7 x 105 erg cm-2 s-1. This is enough to power the corona and solar wind in quiet regions and coronal holes, and therefore indicates that the granule-size emerging bipoles are the main engines that generate and sustain the entire heliosphere. Key words: Sun: heliosphere – Sun: corona – Sun: chromosphere – Sun: surface magnetism – Sun: magnetic topology – Sun: activity Submitted to The Astrophysical Journal Letters January 2011 1 1. INTRODUCTION The heliosphere, the bubble that the solar wind blows in the interstellar wind, is ∼ 104 times bigger in diameter than the Sun.